From owner-freebsd-hackers Mon Nov 10 02:06:51 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id CAA19306 for hackers-outgoing; Mon, 10 Nov 1997 02:06:51 -0800 (PST) (envelope-from owner-freebsd-hackers) Received: from bugs.us.dell.com (bugs.us.dell.com [143.166.169.147]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id CAA19298 for ; Mon, 10 Nov 1997 02:06:47 -0800 (PST) (envelope-from tony@dell.com) Received: from ant.us.dell.com (ant.us.dell.com [143.166.12.34]) by bugs.us.dell.com (8.6.12/8.6.12) with SMTP id EAA18346; Mon, 10 Nov 1997 04:01:02 -0600 Message-Id: <3.0.3.32.19971110035812.00701028@bugs.us.dell.com> X-Sender: tony@bugs.us.dell.com X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.3 (32) Date: Mon, 10 Nov 1997 03:58:12 -0600 To: Terry Lambert , mike@smith.net.au (Mike Smith) From: Tony Overfield Subject: Re: x86 gods; advice? Suggestions? Cc: mini@d198-232.uoregon.edu, hackers@FreeBSD.ORG In-Reply-To: <199711091021.DAA24289@usr06.primenet.com> References: <199711080954.UAA00629@word.smith.net.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-freebsd-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk At 10:21 AM 11/9/97 +0000, Terry Lambert wrote: [Tremendous amounts of nine-fingered vm86 task creation and operational ideas deleted] >This sort of answers Tony Overfield's "3. Something else..." question: >you can get a Task Gate Descriptor in the LDT or GDT or IDT. This means >"Something else..." can be triggered by: Uh no. Let's see if we can follow the thread.... [Here, it's clear that Terry and Tony aren't on the same page. :-( ] In reference to bootloader ideas, and referring to calling the real-mode BIOS calls from the kernel initialization code, Tony asked: > Speaking of vm86(), why not just use real-mode? It's easier and much > better for compatibility while booting. In response, Mike asked (rhetorically, I think) how one could load the kernel into memory without using protected mode at all: >How do you copy the kernel into memory > 1M in real mode? If you could >elaborate on this (and how to *stay* in real mode while running over >1M, ie. so that the kzip pass and subsequent real-mode startup >requirements could be met), I'd be *very*happy* [Here, it's clear that Mike and Tony weren't on the same page. :-( ] Terry's suggestion to load the kernel into memory without using protected mode at all is this: >There are several ways to do this. The main one uses a call that drops >into protected mode, changes a 64k mapping at the top of the 1M >you can get at, and goes back to protected mode. [Here, it's clear that Terry and Mike weren't on the same page. :-( ] Wondered which of the possible "real-mode" only approaches Terry was thinking about, I said: >I can't tell, but I think you're talking about one of these: > >1. ... switching to protected mode, setting larger segment limits > and then switching back to real mode. > >2. ... the real mode trick of using FFFF:xxxx addressing. > >3. Something else. [Here, it's clear that Tony and Terry weren't on the same page. :-( ] So there we are. Terry misunderstood the question asked by Mike who misunderstood the question asked by Tony, who probably asked an ambiguous question to begin with. Sorry. I *never* have this problem with people I already know. Dang this "language" stuff we're forced to use to communicate. ;-/ - Tony